A nitrogen oxide (NOx) contained in exhaust gas in a thermal power station or the like using petroleum, coal, gas, or the like as a fuel is a typical air pollutant besides a sulfur oxide (SOx) and particles of soot. Emission of NOx is regulated by laws. In such circumstances, an exhaust-gas denitration system is conventionally provided in a boiler in a thermal power station, a large-sized boiler of various types, other waste incinerators, or the like. The exhaust-gas denitration system includes a plurality of denitration catalyst layers.
As the denitration catalyst, a honeycomb type and or plate type denitration catalyst is used. If the denitration catalyst is continuously used, a matter that deteriorates a performance of the denitration catalyst adheres or melts out on a surface or inside of the denitration catalyst. This disadvantageously results in a deterioration of the performance of the denitration catalyst. Conventionally, the performance of the denitration catalyst is managed by measuring an NOx concentration and an unreacted NH3 concentration at an inlet and an outlet. If overall performance is deteriorated, the catalysts are sequentially replaced with new catalysts in a descending order of service life on a periodic basis.
The conventional technique has, however, a disadvantage of an increased replacement cost since a denitration catalyst is very expensive. A degree of performance deterioration of the denitration catalyst depends on a manner of use of the exhaust-gas denitration system or a position at which the catalyst is used in the system. Due to this, replacement of even a usable denitration catalyst is sometimes conducted which is an inefficient replacement. In addition, according to an analysis of the applicant, the performance of the denitration catalyst is sometimes recovered by regeneration, which can eliminate the need for replacement.
The present invention has been achieved in view of above disadvantages (problems). It is an object of the present invention to provide a method and apparatus for managing a denitration catalyst that ensure efficient and cost-effective management of a denitration catalyst including regeneration and replacement thereof by comprehensively and intensively managing the denitration catalyst.